2 * Copyright (C) 2004-2006 Atmel Corporation
4 * Based on linux/arch/sh/mm/fault.c:
5 * Copyright (C) 1999 Niibe Yutaka
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/pagemap.h>
15 #include <linux/kdebug.h>
16 #include <linux/kprobes.h>
18 #include <asm/mmu_context.h>
19 #include <asm/sysreg.h>
21 #include <asm/uaccess.h>
24 static inline int notify_page_fault(struct pt_regs *regs, int trap)
28 if (!user_mode(regs)) {
29 if (kprobe_running() && kprobe_fault_handler(regs, trap))
36 static inline int notify_page_fault(struct pt_regs *regs, int trap)
42 int exception_trace = 1;
45 * This routine handles page faults. It determines the address and the
46 * problem, and then passes it off to one of the appropriate routines.
48 * ecr is the Exception Cause Register. Possible values are:
49 * 6: Protection fault (instruction access)
50 * 15: Protection fault (read access)
51 * 16: Protection fault (write access)
52 * 20: Page not found (instruction access)
53 * 24: Page not found (read access)
54 * 28: Page not found (write access)
56 asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
58 struct task_struct *tsk;
60 struct vm_area_struct *vma;
61 const struct exception_table_entry *fixup;
62 unsigned long address;
67 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
69 if (notify_page_fault(regs, ecr))
72 address = sysreg_read(TLBEAR);
81 * If we're in an interrupt or have no user context, we must
82 * not take the fault...
84 if (in_atomic() || !mm || regs->sr & SYSREG_BIT(GM))
90 down_read(&mm->mmap_sem);
92 vma = find_vma(mm, address);
95 if (vma->vm_start <= address)
97 if (!(vma->vm_flags & VM_GROWSDOWN))
99 if (expand_stack(vma, address))
103 * Ok, we have a good vm_area for this memory access, so we
110 case ECR_PROTECTION_X:
112 if (!(vma->vm_flags & VM_EXEC))
115 case ECR_PROTECTION_R:
117 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
120 case ECR_PROTECTION_W:
122 if (!(vma->vm_flags & VM_WRITE))
124 flags |= FAULT_FLAG_WRITE;
127 panic("Unhandled case %lu in do_page_fault!", ecr);
131 * If for any reason at all we couldn't handle the fault, make
132 * sure we exit gracefully rather than endlessly redo the
135 fault = handle_mm_fault(mm, vma, address, flags);
137 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
140 if (unlikely(fault & VM_FAULT_ERROR)) {
141 if (fault & VM_FAULT_OOM)
143 else if (fault & VM_FAULT_SIGBUS)
148 if (flags & FAULT_FLAG_ALLOW_RETRY) {
149 if (fault & VM_FAULT_MAJOR)
153 if (fault & VM_FAULT_RETRY) {
154 flags &= ~FAULT_FLAG_ALLOW_RETRY;
155 flags |= FAULT_FLAG_TRIED;
158 * No need to up_read(&mm->mmap_sem) as we would have
159 * already released it in __lock_page_or_retry() in
166 up_read(&mm->mmap_sem);
170 * Something tried to access memory that isn't in our memory
171 * map. Fix it, but check if it's kernel or user first...
174 up_read(&mm->mmap_sem);
176 if (user_mode(regs)) {
177 if (exception_trace && printk_ratelimit())
178 printk("%s%s[%d]: segfault at %08lx pc %08lx "
179 "sp %08lx ecr %lu\n",
180 is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
181 tsk->comm, tsk->pid, address, regs->pc,
183 _exception(SIGSEGV, regs, code, address);
188 /* Are we prepared to handle this kernel fault? */
189 fixup = search_exception_tables(regs->pc);
191 regs->pc = fixup->fixup;
196 * Oops. The kernel tried to access some bad page. We'll have
197 * to terminate things with extreme prejudice.
199 if (address < PAGE_SIZE)
201 "Unable to handle kernel NULL pointer dereference");
204 "Unable to handle kernel paging request");
205 printk(" at virtual address %08lx\n", address);
207 page = sysreg_read(PTBR);
208 printk(KERN_ALERT "ptbr = %08lx", page);
209 if (address >= TASK_SIZE)
210 page = (unsigned long)swapper_pg_dir;
212 page = ((unsigned long *)page)[address >> 22];
213 printk(" pgd = %08lx", page);
214 if (page & _PAGE_PRESENT) {
216 address &= 0x003ff000;
217 page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
218 printk(" pte = %08lx", page);
222 die("Kernel access of bad area", regs, signr);
226 * We ran out of memory, or some other thing happened to us
227 * that made us unable to handle the page fault gracefully.
230 up_read(&mm->mmap_sem);
231 pagefault_out_of_memory();
232 if (!user_mode(regs))
237 up_read(&mm->mmap_sem);
239 /* Kernel mode? Handle exceptions or die */
242 if (!user_mode(regs))
246 printk("%s%s[%d]: bus error at %08lx pc %08lx "
247 "sp %08lx ecr %lu\n",
248 is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
249 tsk->comm, tsk->pid, address, regs->pc,
252 _exception(SIGBUS, regs, BUS_ADRERR, address);
255 asmlinkage void do_bus_error(unsigned long addr, int write_access,
256 struct pt_regs *regs)
259 "Bus error at physical address 0x%08lx (%s access)\n",
260 addr, write_access ? "write" : "read");
261 printk(KERN_INFO "DTLB dump:\n");
263 die("Bus Error", regs, SIGKILL);